public class Test1 {



}
class Solution {
    public char findTheDifference(String s, String t) {
        int[] arr = new int[26];
        for(int i = 0 ; i <s.length();i++){
            char ch = s.charAt(i);
            arr[ch-97] ++ ;
        }
        for(int i = 0 ; i < t.length() ; i++){
            char ch = t.charAt(i);
            if(arr[ch-97] != 1){
                return ch ;
            }
        }
        return 0 ;

    }
}